1、//加一个随机数//////////////////////////////
var number = Math.random();
number = number * 1000000000;
number = Math.ceil(number);
var url=’get_book.aspx book_num=’+book_num+
‘&ranum=’+number
或 var timespan=(new Date()).getTime;
var url=’get_book.aspx book_num=’+book_num+
‘& timespan =’+ datetime